An indexable rotating tool is proposed that has (a) a body in a shaft shape and (b) a tip concentrically and detachably attached to a leading end portion of the body by screw-fastening and rotationally driven around an axial center O along with the body for predetermined machining. A tap described in Patent Document 1 is an example thereof and has a body disposed with a screw hole concentrically to the axial center O while a tip has a penetrating attachment hole concentric to an axial center O, and an attachment screw penetrates through the attachment hole of the tip to be screwed into the screw hole of the body, thereby integrally fixing the tip to the body. Each of mating surfaces of the body and the tip has concave and convex portions, and the concave and convex portions are meshed with each other to prevent relative rotation around the axial center O.
FIGS. 17 and 18 depict a thread forming tap 150 that is an example of such a conventional indexable rotating tool, which has a tip 156 detachably attached via an attachment screw 154 to a body 152, and multiplicities of meshing teeth 160 and teeth grooves 162 are alternately radially disposed as depicted in FIG. 18 in each of facing surfaces of the body 152 and the tip 156 axially faced with each other and are meshed with each other to integrally fix the body 152 and the tip 156 to prevent relative rotation. FIG. 18 depicts the facing surface of the tip 156, which has the meshing teeth 160 having a width dimension set larger as compared to the teeth grooves 162, and the body 152 has reverse configuration to that of the facing surface of the tip 156. The body 152 is disposed with a fluid supply path 158 in the axial direction and the fluid supply path 158 is branched on the way into multiple i.e., two or more branch paths 159 in a Y shape such that cooling fluid is discharged obliquely forward from the branch paths 159 to cool a portion roll-formed by the tip 156.